Phonograph stylus



Aug. 10, 1943. s. E. PATE PHONOGRAPH STYLUS Filed June 27, 1942 Patented Au 1c, 1943 PHONO GRAPH STYLUS Sherman E. Pate, Chicago, Ill., assignor to Permo Products Corporation, Chicago, 111.; a corporation of Illinois Application June 27, 1942, Serial No. 448,752

4 Claims.

This invention in general relates to phonograph styli and more particularly to a stylus having new and novel construction for controlling the frequency response thereof.

The phonograph industry has long desired and sought phonograph styli which inherently provide means for controlling and limiting the transmission of sound vibrations in predetermined parts of the sound spectrum, and also means for eliminating undesirable sympathetic vibration set up in the needle shank which is one of the undesirable characteristics in phonograph styli of the ordinary variety.

The present invention provides means for overcoming the above objections and constitutes the princ pal object of the invention.

A further object of the invention is to provide a stylus having a substantially rigid shank at one end andterminating in a shank of predetermined smaller diameter at the other end providing a resilient means for absorbing vibrations of certain frequencies and amplitude.

A further object of the invention is the provision of a phonograph stylus having a hollow shank provided for encas'ing a stylus pointed at one end thereof with a viscous material between the casing and the stylus to damp sympathetic vibrations of predetermined frequencies set up in said stylus when playing.

Further objects and advantages will be apparent in the following description of one embodiment of the invention, in which:

Fig. 1 is an enlarged side elevation of my new stylus.

Fig. 2 is a longitudinal cross-sectional view of the stylus taken through section lines 22, Fig. 1.

Fig. 3 is a cross-sectional view of the stylus taken through section lines 3-3, Fig. 1.

The invention is characterized by-a tubular casing I, Fig. l, in the upper end of which is integrally afiixed a stylus 2. The stylus has a predetermined reduced diameter 3 through its free length terminating in a wear-resistant point 4 welded to the said stylus and shaped to provide proper engagement with the grooves of a record. A fragmentary section of a record 5 is indicated in Fig. 2.

Since the diameter of the small section of the stylus 3 is determined by the limitation of the frequency transmission desired, it has been found that because of its relatively small diameter, sympathetic vibrations are set up in the stylus which transmit undesirable sustained vibration in the upper end of the casing I and thence to the pick up in which the stylus is normally secured, This vibration is apparent in reproduction as distortion. This sympathetic vibration is completely eliminated by filling the annular space between the stylus 3 and the casin l with a damping media 6. It has been found that a variety of materials are suited for this purpose including rubber, a non-drying viscous oil such as the petroleum derivatives, or compounds of the plastic family such as cellulose acetate mixed with suitable plasticizer to prevent solidification. In practice a well-known material known as plasticized Pyralin has been found satisfactory.

In operation it has been found that a predetermined frequency response from conventional records may be obtained by choosing a stylus 3 of a particular diameter and filling the cavity between the stylus and the casing l with material of predetermined compliance. It is also possible to alter the frequency response of the composite stylus by increasing or decreasing the diameter of the casing I with respect to the stylus 3.

Having described my invention, I claim:

1. In a phonographstylus, a metallic playing portion having a point at one end, a metallic casing portion, said casing having a substantially concentric bore longitudinal to the casing thereof, said playing portion extending substantially concentrically into said bore and integrally secured therein with its point protruding therebeyond in spaced relation to the inside wall of said casing at the lower end, the annular space between said playing portion and said casing filled with a resilient damping compound, said compound extending in close proximity with the said point.

2. In a phonograph stylus, a metallic playin portion having a point at one end, a metallic casing portion, said casing having a substantially concentric bore longitudinal to the casing thereof, said playing portion extending substantially concentrically into said bore along its principal axis and integrally secured therein with its point protruding therebeyond, said bore being of greater diameter than that of the playing portion at its lower end and the intervening space between the playing portion and the casing thereof filled with a viscous damping media, said media extending in close proximity with the said point.

3. In a phonograph stylus, a metallic playing portion having a playing point, means at the end of said playing portion remote from its point for engagement with a phonograph reproducer, a relatively rigid metallic protecting element inengagement with a, phonograph reproducer, a re atively rigid metallic protecting element integrally aflixed on said stylus, said last named element having one end adjacent to and spaced from said playing portion, said space filled with a plasticized cellulose acetate, said space sufliciently large to permit normal vibration of the stylus but limiting the amplitude of sympathetic vibrations in said playing portion when the said point is 1 engaged in a moving record.

SHERMAN E. PATE. 

